The present invention relates to an advancing device for the motorized vertical displacement of a record carrier in an electrically drive office machine, such as a typewriter.
Such an advancing device is disclosed in German Offenlegungsschrift [Laid-open Application] No. 2,056,564, and corresponding U.S. Pat. No. 3,618,738. The machine disclosed therein contains four operating elements: a first key provided to actuate an advancing movement in the forward direction; a second key provided to actuate an incremental movement in the reverse direction; a first shifting switch provided for a slow continuous advancing movement; and a second shifting switch provided for a fast continuous advancing movement. Each shifting switch can be shifted from a zero position in either of two opposite directions, a shift in the one direction actuating a forward advancing movement and a shift in the opposite direction actuating a reverse advancing movement of the advancing device.
Such a device enables the operator to accurately position a record carrier line by line in the forward or reverse direction and also to perform longer advancing movements at a faster rate and to quickly perform insertion and removal manipulations of the record carrier. However, due to the multitude of operating elements, this prior art device is difficult to operate so that the operator requires a longer familiarization period and the given functions are not utilized optimally.